Process for the production of fertilizers containing phosphoric acid and potassium



UNITED- STATES PATENT oar-ice.

'mnononnnancn, or none, ITALY.

PBOQESS FOR THE PRODUCTION OF CONTAINING PHOSPHORIO ACID AND POTASSIUM.

1 4 1|1- 696 Specification of Letters Patent. Io Drawing in Processes for the Production of Ferti-.

lizers Containing Phosphoric Acid and'Po tassium, of which the following is a specification.

The present invention relates to a process for the production of fertilizers containing 7 phosphoric acid and potassium.

In late years a number of processes have been proposed for the productionof fertilizers containing phosphoric acid and potassium in an assimilable form, but their practical operation ofi'crs great difiiculties since the temperatures of over 1600 C. even of 2000 C. said by various inventors to be necessary are difiicult to attain and the furnaces subjected to such temperatures are quickly destroyed, so that many of the proposed processes cannot be carried out when working continuously. If such processes are carried out in crucible or rotary furnaces the volatilization of potassium and phosphoric acid is a drawback causing considerable losses.

-The present invention aims at obviating these drawbacks and combines the knowledge and experience gained from the known processes for the production of a fertilizer containing in an assimilable form, on the 1 one hand, phosphoric acid, lime and silicicl acid calcium-silico-phosphate), and on the other hand phosphoric acid, potassium and silicic acid (alkali-silico;phosphate), by providing, a process which enables the production of a fertilizer containing phosphoric acid, potassium, lime together with silicic acid in an assimilable form (potassiumlime-silico-phosphate), which fertilizer is of high nutritive value for cultivated plants and which. possesses technically valuable properties as regards preparation, storage, handling and utilization of the products.

According to my invention, the raw materials natural phosphate' and leucite orphonolite or' potassium felspar or other alkali silicates and limestone or marl or both together, are first broken up to form lumps of egg size, and mixed together in such proportions that on melting, products are obtained, which especially as regards the Patented Apr. 4, 1922.

Application filed March 22, 1921. Serial No. 454,421.

' chemical fixation of the phosphorus are most closely akin to Thomas-slag.

The meltmg is effected with coke in a blast furnace which is water-cooled near the meltin zone, an air blast preferably preheated y the waste gases, and which may be enriched-with oxygen being employed. It has been ascertained that the column of the brokenup material fed in" the furnace actsas a filter and as a chemical binder for the phosphoric acid, and potassium volatilized in the melting zone, 'so that the content of these substances in the waste gases isvery much reduced.

The amount of coke added is such that a temperature at which the melt is thoroughly liquid is obtained in the furnace.

The addition of marl instead of lime, re-

quired for regulating the composition of the molten products is also of special importance for reducing the melting temperature and for increasing the temperature if desired the addition of technical oxygen to the blast is of particular importance. The melt is periodically or continuously removed from the melting furnaceby tapping and running-throu h a trough, and on leaving the trough is isintegrated as'finely'as possible by a stream of high-pressure steam, air, steam and air, ir and water, or water alone, and thrown into a chamber formed by wire-netting which retains the particles of dust but allows the air, steam and gases to pass through. The bottom of the chamber is provided with a conveyor which con vVeys the disintegrated molten mass to a grmding plant.

The above described disintegration with high ressure steam, air or water effects first an immediate chilling and solidificationof the molten product, and thusan increased assimilability of the phosphoric acid, potassium and the like, in the case of a correctly proportioned mixture for the producthus assisting grinding, and considerably facilitating the resorption through the roots of the plants. The disintegration of the liquid melt effected in the above described manner produces a complete decomposition of the calcium'sulph'ide injurious to the plant which content of the coke, and renders it harmless.

From the waste gases of the blast-furnace after cooling in dust collecting channels or chambers, after settling and filtration, a dust of high phosphorus and potassium content is obtained which may be added to the finished products during or after grinding. The waste gases of the blast-furnace when not filtered are non-combustible or very dif ficulty combustible. However, after filtration they may be used for preheating the blast for the blast-furnaces.

Claims- 1. The process'of producing a fertilizer, which consists in first breaking up and mixing together phosphates, alkali silicates and lime '(marl), then melting this raw material while maintaining the column of the raw material at a height sufficient for the formation of a filter to cause the mechanical and chemical binding of the phosphoric acid and silicate, and finally removing the melt.

2. In the process as specified in' claim 1,

the further step of disintegrating the melt by means of a blast of high-pressure fluid thereby producing a finely divided product,

and at the same time for the purpose of thereby obtaining a nearlfi complete assimiof the P 0 and 0.

labili tly 3. e process of producing a fertilizer ficientfor the fo'rmationof a filter tocause' i the mechanical and chemical binding of the phosphoric acid and potassium silicate, then reducing the melting temperature,- removing the melt and finely disintegrating it by a high-pressure fluid and collecting the fine particles. V

4. The process as specified in claim 4 in which the fine particles are finally subjected to grinding.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses. 1

THEODORE HAEGlil.

Witnesses:

LETTEN LAno & Mon, WILHELI Scrum). 

